Rotary finger buff



Jan. 12, 1960 E. w. HALL ETAL ROTARY FINGER RUFF Filed Dec. 1v, 1958 2,920,428 1Ce l Patented Jan. 12, 1960 ROTARY FINGER BUFF Elisha W. Hall, Scituate, and Albin S. Rock, East Bridgewater, Mass., assignors to F. L. & J. C. Codman Company, Rockland, Mass., a corporation of Massachusetts Application December 17, 1958, Serial No. 781,070 6 Claims. (Cl. 51-193.5)

This invention relates to rotary finger bulfs for abrading metal, the word abrading being used in the generic sense and covering line polishing as well as more vigorous action.

The expression linger bull is well known in the art yand designates a rotary bufrr having a center from which project radially outwardly elements of considerable length and of substantial cross section, either cylindrical or flattened, the word linger applied to these elements being an appropriate metaphor because they resemble generally in proportion, although not in dimensions, an extended forelinger. The lingers are independent and, although closely arranged, are not pressed together in a mass. In operation they flex individually as their ends move over the work and, while they may make contact with following lingers during operation, are not dependent on them for support. The elastic resistance to such flexing and the resilient recovery of the lingers are factors in the eliective practice of the buliing operation.

In accordance with the invention the lingers are made of short lengths of suitable liber rope sewn through lengthwise to control fraying at their ends. By rope is meant an assembly of libers wherein twisted yarns form strands, and these strands laid up as elements of a rope having an inherent balance of twist maintaining it in form as a unit. If a short section of rope is cut olic the strands do not separate. To remove one 'from the others it must be as it were unwound. On the other hand the end of a rope frays out unless whipped or otherwise bound. When used as lingers the end of'the rope primarily engages the work. To prevent its fraying initially, and as the finger wears away, one or more longitudinal seams are sewn throgh the rope along its length, binding its elements together.

The invention will be well understood by the following description of an illustrative embodiment thereof, wherem:

Fig. l is a partial side elevation of a buliing section illustrative of the invention;

Fig. 2 is a radial section on a larger scale partly broken away;

Fig. 3 is a plan view showing how the fingers are assembled preparatory to mounting on the center;

Fig. 4 shows a rope as used in the lingers, with its parts successively separated to permit their independent designation in the description which follows;

Fig. 5 is a cross section of a four-strand or shroud-laid rope; and

Fig. 6 is a view similar to Fig. 4, showing thev use of rope sections or lingers of different diameters in the same buil section. l f

'I'he words buit section are here used because, while what is shown in Figs. 1 and 2 in a sense is a complete wheel and could be so used, it would ordinarily be assembled side by side with other sections of similar construction to make a wheel of wider face.

tion is such that, as will appear, each section comprises The constructwo annular series of lingers, and that is the most advantageous Way of mounting the lingers for use.

Figs. 1-4 illustrate a buli section wherein the lingers r are formed by short lengths of a three-strand or hawserlaid rope. In particular the rope shown in Fig. 4 is what a cordage maker refers to as a six thread rope, the word thread as here used being equivalent to yarn. Referring to the tigure there appear at the upper right two twistedyarns y of a suitable vegetable liber, for instance sisal, which are twisted together on a pitch opposite to their own twist, to form a strand or ready s. Three of these strands are laid up together on the opposite pitch and in laying up the strands are given an overtwist in the original direction to compensate for this laying up, so that the elementary parts of the rope are in substantial equilibrium. The structure is balanced and the elements do not come apart. If we cut olf a short length of a well made rope the strands do not separate. If we want to take one out we must unwind it. Similarly, the elements of the strand are in balance.

On the other hand it is well known that the end of a rope will fag out and, to prevent progressive deterioration, the end is usually Whipped or otherwise secured. Therefore the rope used for the lingers is stitched through by stout thread lengthwise thereof, and we have herein shown two seams of stitching t extending lengthwise of the rope section at either side of the axis. In Fig. 4 the-lines delineating the surface texture of the strands, which results from the presence of the yarns and the twisting, have been omitted in one place in order to show better the stitching, and the ends of the threads t are shown unraveled toward the middle of the ligure, so that they may more readily be identilied. The stitches extend through the body of the rope as chords of its cross sectional circle and the stitching thread in general will 'intersect more than one strand in its chord-like passages and between said passages directly engage more Ithan one strand along the exterior surface of the length. Thus the strands are bound together as are their component yarns and the 'end of the section does not fray out quickly. As the end of the linger wears away in use lthe seams are not released. Initially the stitching functions as an end whipping, but it is one that is self-renewing as the lingers wear down. It will be clear moreover that, even if the strands did not separate one from another at the end of the linger, if they began to unlay with resultant increase of the pitch of the helix that linger would be lengthened and form a high spot in the wheel as a Whole. The stitching prevents such variations of pitch.

A considerable, but not unlimited, choice is available as to the size and makeup of the lingers. I shall now describe specifically an 18-inch diameter buff mounted on a center eight inches in diameter, as shown in the drawings, this butf being made of lingers of six-thread sisal rope about one quarter of an inch in diameter and about live and one half inches long. Such rope in itself would be like a good quality of sisal clothesline. It is stitched lengthwise in the long length as delivered from the rope maker. In the particular example illustrated the strands have a pitch of about one turn per inch and the stitches rare about eight to an inch. More generally it may be said that there should be several turns of the strand in the length ol. each finger. Several has the usual meaning of two or three or even more, but not many.

To produce the buff shown in Figs. 1 and 2, segments of the rope, each about a foot in length, may be laid together side by side like the logs in a corduroy road, as illustrated in Fig. 2 and secured together at the middle of their length by a tape 10 which may be a tape coated with pressure-sensitive adhesive. This tape is not utilized for strength and, if it is retained in the completed article its presence would be of little or no practical importance, it

being used primarily to permit a group of rope segments to be assembled and handled as a unit in bringing them to their proper relative positions. The tape 10 is herein illustrated in Fig. 2 because it facilitates for the reader the correlation of Figs. 2 and 3. A suitable length of rope segments grouped together as shown is coiled up in the form of a cylinder and then, by pressing the center line (where the tape i is) inwardly and folding the sides outwardly and toward each other, the cylinder is upset into the form of two annuli side by side as seen in Fig. 2, each annulus consisting of a series of fingers, each a short length of rope. This method of forming an annular buff by upsetting a cylinder is well known in the art and it is not necesary to illustrate it. The smaller circumferences of the annuli are secured to a center l2, herein shown as a metal center of the kind shown in the application of Albin S. Rock, Serial No. 677,053, filed August 8, 1957, having means for grappling and holding the rope segments where they are doubled over and in particular these means take the form of teeth 14 relatively offset at the two sides of the center which penetrate between the rope segments and compress the bodies of the same and hold them firmly without utilizing any extraneous ring or binder in the bights of the doubled sections to retain them.

In Fig. 5 i have illustrated a cross section of fourstrand or shroud-laid rope with four strands s', herein shown as each formed of three yarns, y and laid up around a core or heart c to form the rope r. Such a rope may be used instead of a three-strand rope.

Fig. 6 is a view similar to Fig. 3 illustrated an assembly of rope sections alternately of different diameters, for instance one-fourth inch and three-eighths inch and such an arrangement is found advantageous in that streaking on the work is substantially eliminated.

When the rope is made of sisal or similar hard fiber, as fibers are classified by a rope maker, it is harsh and has a vigorous abrading action. It is possible to use in a single buff, in suitable proportions, fingers of harsh fibers such as sisal and fingers of soft fibers such as cotton. The cotton will absorb and carry bufiing compounds better than the sisal, and the sisal will do the abrading.

To facilitate the application of buiiing compound the rope should preferably be soft-laid rather than hardlaid. That is, the amount of twist of the elements, while properly balanced, should not be too great per unit of length. The considerations which prompt the cordage maker to produce hard-laid ropes for some uses do not apply here. Also, high tensile strength, so important in most uses of rope, is not called for and the rope may be made of a relatively inexpensive grade of shorter bers than would be selected for making high grade rope.

The use of fingers of different fibrous material, so that the buff face as such is of a heterogeneous nature, has been referred to. It is preferred, however, to obtain a similar effect by using different fibers in the construction of the rope itself. For instance, referring to Fig. 4, one of the yarns y might be sisal and the other cotton, producing in the rope r as a whole a half-and-half apportionment of fibers. It is believed that to make one strand of a three-strand rope of cotton and the other two of sisal or vice versa, is a less desirable, but possible construction. In general the two fibers should be present in cosubstantial quantities considering the buff as a whole. That is, if they were of mixed cotton and sisal one or the other fiber might be not less than a sixth or more than iive-sixths of the fibers present. The designation by sixths instead of percent is due to the fact that usually the number of elements in a rope will have a factor three.

As has been stated, the dimensions of the fingers may be considerably, but not indefinitely, varied to obtain the desired results in a buff. The cross section of the rope might vary from a diameter of three-sixteenths of an inch to abut iive-eighths of an inch, but dimensions between one-fourth of an inch to one-half inch are preferable.

i There is no rigid limit and in any event the designation of rope by its diameter is to a certain extent nominal. The sailors way of designating rope by its circumference is nowadays less frequently heard, but the two measurements are usually correlated by using three as the value for pi, which illustrates the previous sentence. As has been stated, the drawing represents an eighteen-inch diameter section in which the fingers are about tive and onehalf inches long. Their length will vary with the diameter of the wheel, but the proportions will be substantially similar. The lengh is about two-thirds of the wheel radius and it may be sufficient to say that it may be a major fraction. lf the fingers are too short they will not wear long, and their use would therefore be commercially disadvantageous. If they are too long, they might be too tioppy to operate properly. The length of the stitches may be about eight to an inch.

A yarn such as the yarn y illustrated in Fig. 4, in itself is what seamen call spun yarn and it is also known to twine makers as binder twine, because it is used in binders for grain, and by other names derived from its intended use. A superior quality of spun yarn is known which is two-ply, that is, two yarns twisted together. It has been proposed to make a buff finger from a number of lengths of spun yarn set side by side, enclosed in a sleeve of woven fabric and sewn through. The fabric more particularly holds the yarns together and in general the stitches of the sewing would pass between adjacent yarns. Spun yarn is also packaged in what is called many ends style. That is, a number of yarns are twisted together very slightly, a turn to a foot or more, and wound on a spool. rl`his is done because users require short lengths for various tying operations. For instance, if twenty-five yarns are packaged together in this manner, a single cut will sever twenty-five lengths which practically fall apart, ready for individual use. The cut length has no coherence of its elements and there is no balance of twist. Such a package, however, was convenient for covering with fabric and severing in lengths to form fingers as above described. The rope finger with its balanced twist and the inbuilt coherence of its elements and the cooperative relationship of the stitches to such elements is sharply distinguished from such constructions.

It will be apparent that the invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof, and the present embodiment should therefore be considered in al1 respects as illustrative and not restrictive, as is in fact clear in several matters from the description itself. Reference is to be had to the appended claims to indicate those principles of the invention exemplified by the particular embodiment described and which it is desired to secure by Letters Patent.

We claim:

l. A rotary buff section comprising a center and a multiplicity of independent fingers extending therefrom in two annular groups each being a short length of fiber rope comprising yarns formed into strands which strands are laid up into rope providing a neutral state in the length as a whole, the lengths being self-sustaining in their upstanding position, but capable of exing when their outer ends are moved across a piece of work, the diameter of the rope being between about three-sixteenths and about five-eighths of an inch, the lay of the strands being such that several turns occur in each length, each length being sewn through along substantially its entire exposed length by a series of seams having about eight stitches per inch, the stitches extending through the body of the rope as chords of its cross sectional circle, the stitching thread, in general, intersecting more than one strand in its chord-like passages and between said passages directly engaging more than one strand alongthe exterior surface of the length.

5 6 2. A but as set forth in claim 1 wherein the strands 6. A buff as set forth in claim V1 wherein each length are laid up from several yarns. comprises yarns of harsh fiber and yarns of soft ber in 3. A buff as set forth in claim 1 wherein strand lengths cosubst-antial numbers. of different diameters are used in cosubstantial numbers in substantially uniform distribution about the circum- 5 References Cited in the file 0f this patent fern flhe bufnh. l 1 h t d1 gth UNITED STATES PATENTS asse o lncalm weremsran en s formed of harsh and of soft fibers respectively are used 2493791 Waning Jan' 10 1950 in cosubstantial numbers in substantially uniform ds- 2703472 Petersoil Mar' 8 1955 ltribution throughout the circumference of the buff. 10 2724937 Churchill Nov' 27 1955 5. A buff as set forth in claim 1 wherein each length 2'846827 Peterson Aug' 12 1958 is formed of both harsh and soft bers in cosubstantial 2861401 Peterson Nov' 25 1958 amounts. 

